Mic Pre-Amp with Clipping

Signal clipping is usually avoided in most application, but we can find some useful examples where clipping is intentionally employed in audio processing. One example is signal limiter in SSB or radio transmission.  In radio communication, the source of modulating signal (the audio)  affect the modulation depth and should be limited to prevent cross talking the adjacent channel if the […]

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Scaled +6.6V Reference Using 741 Opamp

To maintain constant current of D1 at 2 mA, this circuit uses combination of negative and positive feedback, unaffected by ambient temperature  variation and unregulated input voltage inconsistency. Reference voltage of 6.6 V is scaled up to give higher  volatage level at output of A1. This reference voltage is determined by breakdown voltage of 1N4611 zener. The scaled output has […]

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Two Op-Amps 60 Hz Notch Filter

Notch filter is a filter that remove a certain B. Ideally a notch filter will remove only single point of frequency  component, but practically it will remove a limited range of frequency spectrum. The spectrum should have very small bandwidth to approximate an ideal notch filter. The circuit diagram design below is based on passband gain of 3 and Q […]

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